Climate of Africa PDF

UNIT TWO = 9 period 2. CLIMATE OF AFRICA  Introduction In unit one, you have learnt about landforms of Africa In this unit , you will learn about Climate of Africa This unit has four main sections. In the first section you will learn an Overview of World Climatic...

UNIT TWO = 9 period 2. CLIMATE OF AFRICA  Introduction In unit one, you have learnt about landforms of Africa In this unit , you will learn about Climate of Africa This unit has four main sections. In the first section you will learn an Overview of World Climatic Regions and climatic zones In the second section, you will learn the features of the climate of Africa In the third section, you will study Benefits of Climate for the Life of People In Africa In the last section, you will study Climate Change and the challenges posed by climate change on the development vision of Africa  Introduction… Climate is an average of weather conditions in a place over a long period – 30 years or more. – It represents the sum of all interacting atmospheric processes over a given period. Weather, on the other hand, refers to a short term state of atmospheric condition with respect to temperature and precipitation on a certain day such as hot or cold, wetness or dryness, calm or storm, clearness or cloudiness, sunny or rainy, windy  Introduction…. Climatic zones are large areas with a similar or distinct climate type. The world has several climatic zones such as Tropical, subtropical, Temperate and polar zone Generally, climate zones are belt- shaped- means spread in an east- west direction around the Earth and circular around the poles. They can be interrupted by mountains or oceans in some areas  Introduction…. Climatic region refers to a continuous geographic area with a similar climatic zone – Average temperature is the most important factor in determining climate regions of the world, although other weather aspects like precipitation play roles. Global climate is a description of the climate of the our planet Earth as a whole, with all the regional differences averaged  Therefore, after completing this unit You will be able to: Assess the climate type and climatic regions of the world; Compare climatic regions within Africa; Examine how climate provides substantial benefits for the life of people in Africa; and Analyze the challenges posed by climate change on the development vision of Africa.  2.1 Overview of World Climatic Regions & Types under this section we will learn about – Climate Classification of the world and – Climate Zones and Climatic Regions of the world At the end of this section, you will be able to: – distinguish the different Climate classification schemes of the world and – identify the major climate types  2.1.1. Climate Classifications At the end of this lesson, you will be able to: Identify the climate types and regions of the world  Start up questions What is the purpose of climate classification or why the classification is important? How do climate scientists classify world climates into different types? What are the major climate classification schemes of the world? What are the main climate types? – according to the ancient Greeks – according to koppen what criteria had used in climate classification? – By ancient Greeks? And – by Koppen The function or purpose of climate classifications To know the climate condition a region, usually experiences throughout the year. To choose house building style for protection and durability to consider what crops are likely or unlikely to thrive in a region. to select and pack appropriate clothing during tour to a region ….. Climatologists or climate scientists classify climate of the world into different climate regions or types based on certain criteria. The criterion could be: – temperature – Precipitation or humidity – Latitude /angle of the sun – Vegetation in absence of metrological stations They could be used more than one criterion at once They have been made various classification schemes for categorizing world’s climate into different climate regions.  The main Climate classification schemes are a. The ancient Greeks Climate classification and b. The Köppen Climate classification scheme Since the beginning of the 20th century, however, many other climate- classification schemes have been developed. For instance climate classifications made by two American climatologists, – C. W. Thorn Thwaite and – G.T. Trewartha can be mentioned  C. W. Thorn Thwaite He Presented his first scheme of climate classification of North America in 1931 and published the climatic map of North America. Later he extended his scheme of climatic classification for the world in 1933. He further modified his scheme and presented the revised climate classification of the world in 1948. His scheme of climate classification is complex and empirical in nature. G.T. Trewartha Made several revisions and modifications in the climatic classification of Koppen since 1930s and ultimately presented his simple climatic classification having a blending of both empirical and genetic schemes of climate classifications of the world.  a, Ancient Greeks climate Classification It perhaps one of the first attempt made by Ancient Greeks to classify climate of the world in to three major climate zones based on latitude and angle of the sun (sunshine distribution) these are – Torrid (tropical) zone – Temperate zone and – Frigid zone Figure 2.1: World Climate Zones According to Ancient Greek  b, Koppen’s Climate classification Scheme One of the most widely used and accepted climate classification schemes Made by Russian born, German Climatologist and Botanist Wladimir Köppen (1846-1940). Koppen uses easily obtained meteorological data: mean monthly and mean annual temperature and precipitation to classify the climate In absence of meteorological station, he uses the distribution of natural vegetation as the best expression of an overall climate. He divided the world’s climates into six climatic zones and designated each climate zone with a capital letter: A, B, C, D, E and H A-….Moist tropical climate – Af, Am and Aw B – dry climate – arid and semi arid climate C - Moist middle-latitude with mild winters – subtropical moist marine and Mediterranean climate D - Moist middle-latitude with severe winters – subpolar and humid continental climate E – polar climate ( ET and EP) H – Highland climate- can be found in any latitude The first Four groups (A, B, C, D) are defined by precipitation. The fifth one (E) used temperature as its primary criterion, The sixth one (H) is determined by altitude. – The characteristics of the H- climate zones change with great altitude differences within a small area, like in mountain areas, since temperatures decrease rapidly with altitude  Summary of Koppen’s classification Major climate and sub divisions A- Moist Af- Tropical Rainforest Tropical Am-Tropical Monsoon Aw- Tropical Wet and dry climate B- Dry climate BW- dry Arid climate BS- dry Semi arid climate C- Moist Cfa – moist sub tropical middle-latitude climate with mild Cfb/c- moist sub tropical winters marine Cs- Mediterranean dry summer D- Moist middle- Dfa/b- humid Figure 2.2: Map of Köppen’s Five Principal Climate Groups  2.1.2 World Climate Zones The climate of the earth is driven by energy from the sun which arrives the earth’s surface in the form of radiation. Solar radiation or the sunlight reaches parts of the Earth at different angles, – It reaches the ground almost on perpendicular angle (90°) at the equator, - highest angle of the sun at the equator – receives more radiation – It does not reach the ground or only partially appear on the horizon at the pole circle, lowest angle of the sun at the poles – receive less radiation – Thus, the sunlight warms up the area around the equator much more strongly than the poles There are four major climate zones of the world: These are: Tropical, Subtropical, Temperate and Polar/cold climate zone 1. Tropical Zone It is located between two tropics (0°– 23 ½ N/S) It is the region between the equator and the tropics It receives solar radiation almost the entire year nearly vertically at noontime. it is very warm all year round - high temperature year round, It has more water evaporates and the air is often moist, frequent and dense cloud cover  ii. Subtropics Zone It is located b/n 23.5°– 40° N/S It receive the highest radiation in summer, since the angle of the sun at noon is almost vertical during summer season, whilst the cloud cover is relatively thin. It receive the lowest radiation in winter , the radiation decreases significantly, and it can temporarily be very cool It receives less moisture (dry trade winds) Therefore, It has most of the deserts in the world  iii. Temperate Zone It is located 40°– 60° N/S the solar radiation arrives at a lower angle, and the average temperatures are much cooler than in the subtropics. The seasons and day length differ significantly in the course of a year. The climate is characterized by less frequent extremes, more regular distribution of the precipitation over the year and a longer vegetation period – therefore, it is named as “temperate”  iv. Cold Zone It is located between from 60°– 90°N/S It receive less heat through the year, since there is very low angle of the Sun. Because of the changes of the Earth axis angle to the Sun, the day length varies most For instance, polar days occur in the summer. Vegetation is only possible during a few months in a year and even it is often sparse. The conditions in these regions make life very challenging. Figure 2.3: World Climate Zones What do you understand from fig 2.3: World Climate Zones Africa and Australia have Tropical and Subtropical climate zones. South America has Tropical, Subtropical and temperate climate zones Europe and North America have Subtropical, Temperate and polar climate zones Asia has all major climate zones of the world  Group Assignment - Problem based learning Prepare a sketch of the climatic regions and types of climates of the continents on a flip chart  Evaluation 1. What are the major global climate zones or the main climatic zones of the world? 2. Which Climate zone of the world receives more solar radiation almost the entire year or very warm all year round? 2.2. CLIMATE OF AFRICA Contents: 2.2.1. Major Climatic regions of Africa 2.2.2. Factors Controlling Climate of Africa At the end of this lesson, you will be able to Explain the relationship between position of Africa and its climate types Identify eight climate regions of Africa Explain the characteristics of each climatic regions of Africa Identify the factors that control climate of Africa  Start up questions Explain the characteristics of the climate of Africa Explain the relationship between position of Africa and its climate types. How many climatic regions can we find in Africa? What are they? Characteristics of Climate of Africa The climate of Africa is characterized by a wide range of climate types (it has very diversified/several climate type) The climate of Africa is more variable in rainfall amount than in temperatures Precipitation intensity is always high in Africa, and Warm and hot temperature prevail all over Africa except in Its northern part, which is marked by aridity and high temperatures. The relationship between the position Of Africa and its climate zone Since Africa extends into both northern and southern hemispheres (37°N to 35°S). The position of Africa is relatively unique in the sense that it almost has a mirror image of climate zones of the north and south of the Equator regarding latitude. Because of its location most of Africa lies in the torrid zone/ the most tropical of all the continents As the equator passes through the middle the continent, it receives direct sun rays during the year and experiences hot climate throughout the year. hence , it is the hottest continent of the world Africa is surrounded by Mediterranean sea to the north, Atlantic Ocean to the West and Indian Ocean to the east. Hence it experiences moderate climate along its coastal areas …. Ocean currents: The cool Canary and Benguela Ocean currents wash the North western and South western coastal areas of Africa respectively, have a cooling effect on area. They do not pickup moisture bcs of warming up. While the Mozambique warm Ocean current washing the south eastern coastal areas of Africa, carries more moisture b/se of cooling dawn Elevation/altitude The plateaus which are a higher in elevation, are cooler than the lowlands 2.2.1 The Climatic regions of Africa the climate of Africa is divided in to eight climatic regions on the basis of the movement of air masses and their effects These are 1. Equatorial climate region (tropical wet) 2. Tropical wet and dry – tropical continental or Savanna climate 3. Semiarid climate– climates of semi deserts 4. Arid climate– climate of hot deserts of Africa 5. Warm temperate western margin- Mediterranean cli. 6. Warm temperate eastern coast climate – tropical Maritime climate- Mozambique 7. Warm temperate continental climate – Highveld 8. Mountain/highland climate regions.  I. The Equatorial Climate Region of Africa It is experienced in the lowland area between 5°N/S of the equator. It is dominant in Western and Central Africa, In countries such as Democratic Republic of Congo (DRC), Republic of Congo, Gabon and Cameroon and also southern Nigeria, Ghana, Benin and Sera Leone and the East African Highlands, especially the Eastern highlands of Africa experience modified equatorial climate where the temperature is much lower than true equatorial climate. Dominant in the Congo basin and the east African highlands The climatic region is assumed symmetry around the equator, although the high altitudes in some parts of the continent and the adjacent disturb the symmetry.  The basic characteristics of Equatorial climate high average temperature throughout the year, about 26°C annually, and rarely falling below 21°C. small the annual range of temperature (b/n 1°C to 3°C) March and September the hottest months in the region- the time when the sun is overhead at the equator heavy cloud cover and high humidity all year round high amount of total annual rainfall, normally exceeding 1,500 mm per year, and it reaches 3,200 mm in some places with rain falling throughout the year It is the wettest region in Africa The dominant rainfall type is convectional or thermal rainfall with heavy downpour every afternoon  The Equatorial region is characterized by : High temperature and high rainfall year round due to High angle of the sun and rain falling throughout the year – make the region unpleasant High mean monthly and annual temperatures; High daily range but low annual range of temperature; High total annual rainfall Climate Regions in Africa  II. The Tropical Wet-and-Dry Region It is also called tropical savanna climatic region It is found between 5°and 15° N and S of equator, covering the Central, Southern and Sub Saharan Africa. It also occurs in many parts of Western Africa and Southern Africa and in most of Madagascar It covers a little less than half of the total surface area of the continent ( covers very large area of Africa) by extending from the semiarid areas and surrounding the equatorial region.  Basic characteristic of Tropical wet and dry climate region of Africa very hot summer with an average temperature of 25° C, and cool winter, with an average temperature of slightly above 15°C. high daily mean temperatures averaging more than 30°C in its northern section throughout the year, with relatively lower temperatures in its Southern and eastern sections, due to higher altitudes the mean monthly temperatures show less variation than daily temperatures the same as like the desert and semiarid climatic zones slightly higher annual ranges of temperature than the equatorial climatic zone, with the annual temperature range increasing with distance from the equator  …. The great distinguishing feature of this climatic region is the seasonal character of its rainfall. This means it has distinct wet and dry seasons (6 months wet and 6 months dry in a year) Wet season - During the high angle of the sun, the maritime air masses produce up to six months of rainfall, but in a few places, for example, on the coast of western Africa ( Mauritania and Senegal) Dry season- there is a little rainfall in the period of low angle of the sun, which corresponds to the harmattan wind  The harmattan is a warm and dry … northeasterly wind that blows out from the southern Sahara and is frequently loaded with large quantities of sand and dust It has annual total rainfall ranging between 500 and 1,500 mm per year the length of the rainy season depending on the nearness to the Equator, i.e Part of the savanna which near to the equatorial rainfall region receives high rainfall and rainfall amount decreasing as the distance from the equator increases north and southwards Climate Regions in Africa  III. Semi-arid Climatic Region It is being found at the fringe of tropical deserts its temperature is about the same as the desert regions, but characterized by relatively wetter, receiving more rainfall than the deserts Total annual rainfall is about 250 - 500 mm/year. It is the climate of the Sahel region  IV. The Hot Desert Climatic Region The deserts of Africa are the sunniest and the driest parts of the continent, owing to the prevailing winds of the subtropical high with subsiding, hot, dry air masses. They are characterized by little or no rainfall (less than 250mm) and extremely high mean monthly and annual temperature There are two types of hot deserts in Africa. These are – the coastal desert and continental desert  … i, The coastal deserts are the cool and dry deserts found along the North and south western coast of the continent, these are the Namib desert and western Sahara desert They are caused by cool body of water (Cold ocean currents) flow over the area. These are- the Canary cold ocean Current-that formed the western Sahara Desert –in the northwestern coast of Africa and the Benguela ocean Current –that formed Namib Desert - in the South Western coast of Africa  They are making the area cool and dry … They currents supply low moisture content or bring no rain to the area they flow over – form a fog, Cooling and dry effect–and cause the stable nature of the maritime air masses on the coastal areas, because, the winds are deprived of their moisture as they tend to absorb heat rather than deposit moisture.  … ii, The continental deserts - are located central landmass of Africa or inland regions of Africa These are the Sahara desert in the north and Kalahari desert in the south, which are always under the influence of dry continental tropical air masses the climate regions within the interior of a continent are not affected by winds from the oceans.  In Hot deserts areas of Africa …. The skies are clear and because of this, During the day temperature is extremely high; which usually range between 30ºC - 40ºC, Some places in the Sahara Desert experience above 40°C, The highest ever recorded temperature in the region, and also in the world, was 58°C in Azizia, Libya. At night, temperature is very low, dropping to below 10ºC (even below freezing point in winter), the heat received during the day is quickly lost back into the atmosphere at night due to clear sky High diurnal (daily) range of temperature which even greater than the annual range of temperature.  V. Tropical Maritime Climate region It is also called The Warm Temperate East Coast Climate or humid subtropical marine climate It is restricted to (found only in )southeast coast of south Africa, dominating areas along the Natal and Cape Provinces, as well as in Mozambique and extends roughly to Dar-es- Salaam in Tanzania. It is under the strong influence of the Mozambique warm ocean current and the southeast trade winds – which bring moisture to area. It has heavy rainfall almost throughout the year, averaging between 1000 - 1500 mm per year but RF is decreases as one moves westwards into the interior.  …. It has high temperature throughout the year, with summer being the hottest season (with an average of about 26ºC) , and winter being warm (averaging about 10ºC). It has Low annual range of temperature, which is similar to the equatorial climatic region, but relatively higher range of Temperature than the equatorial climatic regions, though not as high as in the tropical savanna climate. Climate Regions in Africa VI. Warm Temperate Continental Climate Also called Warm Temperate upland Climate It is confined to the in the interior of south Africa , especially to the Highveld grasslands between the Drakensberg Mountains and the Kalahari Desert It has similar rainfall pattern to tropical wet and dry climate, but altitude significantly modifies the temperatures. The rainfall amount is generally lower or much drier than coastal area. For instance, the Eastern part of Highveld is wetter than its Western part as close to the Kalahari Desert. because the winds blowing from the sea reach here when they are already loss their moisture. Most of the rain falls during the winter season with averaging about 700 mm per year.  The annual average …. temperature ranges from about 26ºC in summer to about 10ºC in winter. The temperature and rainfall conditions of Warm Temperate upland Climate region are influenced/controlled mainly by the high altitude and the onshore winds that originate from the Indian Ocean. It is the smallest of all the climatic region in the continent. Climate Regions in Africa VII. Mediterranean Climate Region also called Warm Temperate Western Margin Climate Found in the northern and southern extremities of Africa – in the northwestern tip of Africa - in the Maghreb region, found from Morocco to Libya and – in the southwestern tip Africa found in the Cape Province of South Africa Its temperatures range from 10ºC in winter to about 21ºC in summer. It has hot and dry summer and cool and wet winter In the summer season, the winds blow from the land to the sea, offshore /dry winds Therefore, Summer is dry season  …. In winter the winds blow from the sea/ocean to the land- onshore winds -moist equatorial westerly winds blow from the Atlantic ocean towards the land and bring moisture to the area, therefore, most of the area receives rain fall in winter, with an average amount of 500-750mm each year. Thus it is the only region that gets rain in winter. The influence of moist westerly winds makes the winter mild wet season, which in turn makes the region unique in its climatic characteristics. As a result, the region is one of the most attractive climatic region in the continent. Many tourists visit the region every year  Characteristics of Mediterranean climate It has hot and dry summer season- It experiences high temperature and but no rainfall in summer It has cool and wet winter season - it experiences moderate temperature and receives moderate rainfall in winter Also it has Warm and dry spring and autumn seasons Climate Regions in Africa  VIII. The Mountain/Highland Climatic Region predominantly found in the high mountain areas of the eastern Africa, such as high mountain areas of Kenya, Ethiopia and the lakes region of East Africa The tropical nature of the region is modified by high altitude and thus this climatic region has low Temperature with small annual ranges and this makes it similar to the temperate climate region of the world In some respects, … it also similar to the warm temperate upland climate, it is similar with polar climate where the temperatures are lower and even below freezing point on some tops of the highest mountain peaks that are covered by permanent snow, such as Kilimanjaro and mt Kenya. It is also experiences high rainfall, mainly of orographic or relief rainfall, formed as the warm moist winds are forced to rise up the highlands and have a cooling effect  The slope facing towards the moist … warm wind/the sea- is called windward side- receive the highest amount of rainfall The slope facing away from the sea called leeward side or rain shadow, receive little or no rain , as the winds here are descending and have a warming effect. As altitude increases, Rainfall will increases and Temperature will decreases. At the very top of high mountains, temperatures are below freezing point. 2.2.2 Factors Controlling Climate of Africa At the end of this lesson you will be able to Identify factors that controls the climate of Africa?  Startup Questions What are the factors that influence the climate of Africa? How do these factors control the continent’s climates?  Presentation There are several factors that influence the climate of the African continent. These include – Latitude – Air pressure – Wind system and the ITCZ – Ocean currents, – Land and water (maritime versus continental) influence, – Altitude etc They determine the amount, intensity and duration of temperature and precipitation.  I. Latitude the distance of places from the equator towards the poles It affects the amount of incoming solar radiation the place receives, and thereby its temperature Much of Africa (nearly 2/3rd ) lies within the tropics or in the torrid zone, which receives direct sun rays during the year and experiences hot climate throughout the year. hence , Africa is the hottest of all continents or the most tropical of all the continents  … Africa straddles between 37⁰ N and 35⁰ S latitudes, (it extends into both northern and southern hemispheres ) The Africa does not extend much beyond 35⁰ North and south the equator. The position of Africa is relatively unique in the sense that it almost has a mirror image of climate zones of the north and south of the Equator regarding latitude. Thus, in Africa, the Variations in the receipt of solar energy and temperature differences are largely a function of latitude. As latitude increases, the sun shines more obliquely and provides less energy.  II. Pressure belts, Winds, and the ITCZ The main pressure belts that affect the climate of Africa are include: – The subtropical high (horse latitude) pressure belt around 30⁰ N and S of equator – the equatorial lows (doldrums) pressure belt between 5⁰ N & S latitudes The main winds that affect the climate of Africa  are The trade winds - dominate the climate of Africa  Much of Africa lies within the trade wind belts. i. The NE Trade Winds (locally called Harmattan). The Harmattan is dry and cool wind, blows from the northeast towards SW over Sub- Saharan Africa from November to April loading large quantities of sands and dusts ii. The SE Trade Winds- moist and warm wind blows from SE and bring rainfall to the coastal areas of Africa.  The Guinea monsoon winds (equatorial westerly) also have significant impacts on the climate of coastal and equatorial areas of Africa  ….The range of climatic conditions is limited to tropical Africa and the general direction of wind movement is towards the equator (equatorial low belt or doldrum) Figure 2.6: Major winds that affect the climate of Africa The Inter Tropical Convergence Zone (ITCZ) It is area of low pressure, that encircles the earth near the equator and where the trade winds meet each other It has a significant impact on the climate of Africa, affecting the rainfall pattern and creating wet and dry seasons Shifting in its location following changes in the position of OHS, causes the annual alteration of wet and dry seasons in tropical Africa or equatorial regions of Africa. ITCZ… – In July, summer season, when the sun is overhead at the tropic of Cancer, the ITCZ is located at about 130N, at the southern boundary of the Sahara, in North Africa, pulling the winds toward it. – Hence, the moisture laden winds (Guinea monsoon or equatorial westerly winds) from the Atlantic ocean and the moist SE trade winds from Indian Ocean invade many parts of Africa north of the equator, causing heavy rainfall in the coastal areas of Africa, the highlands of Ethiopia , and eastern part of Madagascar … In January, winter season, when the sun is overhead at the tropic of Capricorn( the sun is low in the northern hemisphere), the ITCZ moves southward along the coastal areas of West Africa to the northern and eastern margins of the Congo basin and continues to Madagascar, Hence, mainly lies over eastern Africa and Indian Ocean – the northeast trade wind - carrying limited or no moisture from Asian continent and from southern Sahara desert blows southward over Africa. Therefore, Northern parts of Africa remain dry, except the Maghreb region, … the SE trade winds bring moisture from Indian Ocean and gives maximum rainfall to Southern Africa and similarly the moist equatorial westerlies from the Atlantic Ocean gives the Congo Basin rainfall Therefore, the position of ITCZ in different season, controls the distribution of seasonal rainfall in Africa. Figure 2.5: The Position of I.T.C.Z in Africa January and July  III. Major Ocean Currents They are the horizontal movement of oceanic water Based on their origin, ocean currents are of two types. i. Warm Ocean Currents- Ocean currents that flow from low latitudes (near to the equator) towards higher latitudes (towards the pole). example- The Mozambique and The Guinea Warm Ocean Current ii. Cool Ocean Currents: Ocean currents that flow from higher latitudes towards low latitudes (towards the equator) They dictate the temperature and moisture characteristics of the winds of the coastal regions over which the they blow. i. Warm Ocean Currents They have high temperatures and high moisture content - warm and wet effect They have warming effect on the adjacent coastal areas of Africa They tend Supply moisture to winds blowing over them to bring rainfall to the coastal areas. Example : The Guinea Warm Ocean Current - in West Africa and The Mozambique Warm Ocean Current– in Southeast Africa  ii. The Cool Ocean Currents They supply low moisture content to winds blowing over them, bring no rain to adjacent areas they flow over - form a fog and Cooling effect–, making places they flow over very dry and desert. Because, the winds are deprived of their moisture, so they tend to absorb heat rather than deposit moisture They Cause dry conditions on coastal areas. Example: the Canary ocean Current- in the northwestern coast of the Sahara Desert – making the area cool and dry the Benguela ocean Current – in the South Western coast of Namib Desert - making the area cool and dry They tend to create rich fishing grounds. Example – Rich fishing grounds exist along the Morocco and Spanish Saharan Coasts and the Namibian coast are washed by the Canary cool ocean Current and Benguela Cool ocean Current respectively Figure 2.5: The major ocean currents affecting the climate of Africa  IV. Distribution of Land and Water Large water bodies such as the Ocean, seas and huge lakes modify climates in adjacent lands or they have great impacts on the temperature and rainfall conditions of adjacent lands. In the continental interior, where there are no large bodies of water, temperatures get very warm during the day and in summer The land is solid, so it heats up more rapidly at the day Due to the compact nature of the land, only a thin surface of the land gets heated. As a result, heat absorbed into the thin layer of surface rocks is released very rapidly at night, thus, The land surface is very cool at night and in winter. … Africa in its northern part is very wide and much of its area is far from the sea. In addition, the extensive plateaus of Africa, which almost reach the coast with steep edges, form barriers greatly reducing the influence of the sea. Furthermore, the continent’s relatively straight and smooth coastline also reduces the impact of the sea in the interior areas. … Therefore, – the distance of the interior of Africa from water body, – the barriers formed by steep edge of extensive plateau reach the coast of Africa and – the relative straight and smooth coastline of Africa Do not allow rainfall to reach the interior continent and thereby creating hot and dry climates As a result, many parts of interior continent experience continental climates with insignificance maritime influence.  … These extremities in climate affect all states located in the interior of continents. Continental Climates, experienced in the interior location and Maritime Climates, experienced on lands located along coasts. places such as Timbuktu in Mali the diurnal and annual ranges of temperature are very high because of continentally. V. Altitude Since light energy from the sun is transformed into heat energy on the surface of the earth, The atmosphere is heated from below (by the earth) not directly by the sun. that’s why we feel colder at mountain tops than in valley bottoms. The air temperature decreases with altitude increases, at an average rate of 6.4o C per 1000 meters. The normal change in temperature with altitude is called the Lapse Rate.  Because of the decrease in temperature with ….. height, temperature is lower in higher altitudes. For instance, Eastern Africa, despite its closeness to the equator, experiences highland climates. Similarly, the Atlas Mountains of North Africa and the Cape Ranges of South Africa experience the coldest temperatures in the continent Very high peaks such as Mountain Kilimanjaro located along the equator even have permanent snow cover. Much of Africa is plateau and high mountains, especially in Eastern Africa. These plateaus and high mountains have great impacts on the continent’s climate.  ….. The plateaus and high mountains reduce maritime influence and reduces temperature. In Africa, the impact of altitude on climate is highly pronounced in the areas of the Atlas mountains the Cape Range-Mountains, and the extensive East African Highlands. While these factors help to account for the broad climatic patterns of African continent, there are nevertheless numerous local variations to be found from place to place within the same climatic zone. Problem based learning One of the factors controlling the climate of Africa is angle of the sun. how do you experience the seasonal differences in angle of the sun in your local areas.  To summarize The following are among the factors that affect the climate of Africa – Latitude affects the climate of the western, northern and Central areas of Africa – Altitude – affects the eastern and Southern highlands of Africa – ocean currents – affect the climate of the coastal areas of Africa. – distance form the sea – affects climates of the northern and Central parts of Africa – Winds and atmospheric pressure belts – affects almost all climate parts of Africa.  Stabilization 1. Latitude- influences climate through the variations in the receipt of solar energy and temperature differences at different latitudes. Particularly, area near the equator receive high angle of the Sun hence have warm climate all the year-round. 2. The Subtropical High-Pressure Belt- Located on both sides of equator, about 30o North and South latitude - dictate surface wind patterns and influence rainfall and temperature regimes on the continent. The STHPBs- generates two wind systems that converge on the equator in a zone termed as ITCZ  … 3. Major Ocean Currents- Warm Ocean currents - flow from low latitudes (near to the equator) towards higher latitudes and carry warm ocean water into relatively cool regions. They have warming and wet effect on the bordering areas. Cold Ocean currents - flow from higher latitudes towards lower latitudes and carry cool ocean water into relatively warm regions and have cooling and dry effect Warm Ocean currents - flow from low latitudes (near to the equator) towards higher latitudes and carry warm ocean water into relatively cool regions..  … 4. Distribution of Land and Water Large water bodies such as the Ocean and huge lakes modify climates in adjacent lands. In the continental interior, where there are no large bodies of water, temperatures get very warm in summer or during the day. 5.…Altitude Since energy from the sun is transformed into heat energy on the surface of the earth, air temperature decreases with an increases in altitude at an average rate of 3.5o F per 1,000 feet of 6.4o C per 1000 meters) called the Lapse Rate. Because of this decrease in temperature with height,  mountainous regions such as the Ethiopian highlands have very cool temperatures.  Very high peaks such as Mountain Kilimanjaro located along the equator even have permanent snow cover.  Evaluation list the five controls of climate of Africa. how does latitude affect the climate of Africa? how does altitude affect the climate of Africa? what is the effect of warm and cool ocean currents on the climate of adjacent areas? is the ITCZ a high-pressure or low- pressure cell area? 2.3 THE ROLE OF CLIMATE ON LIVES OF PEOPLE in AFRICA Contents 2.3.1. Climate and Agriculture in Africa 2.3.2. Climate and Health in Africa 2.3.3. Climate and Water Resources in Africa At the end of this section, you will be able to: explain the role of climate on the lives of people of Africa  Start up questions Explain the role of climate on the lives of people in Africa. Discuss how climate: fosters agriculture, creates a healthy environment, and sustains water resources..Debate on the benefits and disadvantages of climate on the life of the people of Africa The role of climate on lives of people Climate plays an important role in determining our basic needs from what type of food we eat , type of shelter we live in and what type of clothes we wear to where we go for recreation/holiday as well as to what type of occupation and activities we could perform etc For example people living in colder regions, would eat food that give more of heat to keep them warm whereas people living in hotter area would eat food which have cooling properties. Climate has a huge effect on our Livelihood, health, and future... Climate determines what type of vegetation, animals, birds, insects etc, are found in a region, like polar bears found in polar region, whereas camels found in desert areas. It determines the distribution of flora and fauna in the region Climate affects population distribution. For instance, Some places are overpopulated due to the better climate and associated factors. On the other hand, Other places/ regions have fewer people due to extreme climatic conditions like the deserts, rainforests, and the polar regions.  … Climate influences the living style of people including settlement patterns, livelihood options, resource endowments, health ,and wellbeing. Climate, especially temperature and rainfall, affect the distribution and health of ecosystems. It largely determines the agricultural activities, and the materials available for shelter and clothing Hence, people largely depend on ecosystem services for making of agricultural tools, building houses, hunting, etc. It plays significant role in people’s lives by sustaining agriculture creating healthy environment, and providing vital water resources etc  2.3.1 Climate and Agriculture Agriculture is the backbone or an extremely important sector of Africa’s economy and accounts for the majority of livelihoods across the continent, on average, it accounts for 70% of the labor force and over 25% of the GDP. Most of Africa relies of rain fed agriculture, that has always been profoundly dependent on the weather, with farmers needing a steady mixture of sun, warmth, and rains to reliably produce the crops they need. The majority of agricultural systems in Africa, mainly the Sub-Saharan Africa, are highly climate- related activities such as, crop production and livestock husbandry  …. Africa is highly vulnerable to climate change or highly affected by climate change mainly for two reasons: i. Its strong economic dependency on climate related activities and products- the strong dependency on rain-fed agriculture and natural resources ii. Its low adaptive capacity to the impacts of climate change. This low adaptive capacity is linked to weak economies, weak institutions, few technological inputs, small-scale or subsistence level faming and few financial resources, limited access to infrastructure, and, etc. in the continent.  2.3.2 Climate and Health in Africa Climate change has widespread effects on human health by impacting both environmental and social determinants. Climate change has a critical health implications. Changes in rainfall will affect the presence and absence of vector and water born diseases. For Example: it can be expected that small changes in temperature and precipitation will boost population of disease -carrying mosquitos and result in increased malaria epidemics. In many places in Africa, one can expect that climate may readily produce droughts or floods as an almost annual event – An increased flooding could facilitate the breeding of malaria carriers in formerly arid areas – A drought can lead to crop failure and hunger, and – An extreme temperatures pose a risk of exposure.  …Furthermore, in areas where desert climate prevails, the influence of climate on a disease widespread can be difficult to diagnose. all climate impacts on health are mediated by some combination of natural and human dynamics that cause individuals or populations to be vulnerable to the effects of a variable or changing climate. Africa is commonly described as a “climate-vulnerable” continent in which rainfall variability, hydrological extremes, and anthropogenic climate change have the potential to impose significant harm on a large population. 2.3.3 Climate and Water Resources in Africa Water is the most important of all natural resources. Without water ,life would not be able to flourish on the Earth. It has been argued that the level of streams, flow of streams, the volume of underground water and the like all depend on types of climates and water availability. Therefore, persistent climate change may lead to shrinkage in the surface- water supply as well as the quantity and regularity of streams and rivers, and water supplies in Africa.  Stabilization Climate affects nearly every aspect of our lives. It plays a significant role in people’s lives by sustaining agriculture creating healthy environment, and providing vital water resources etc It plays an important role in determining our basic needs from what type of food we eat , type of shelter we live in and what type of clothes we wear to where we go for recreation/holiday as well as to what type of occupation and activities we could perform etc  Stabilization…. It has a huge effect on our livelihood, our health, and our future. Climate determines what type of vegetation, animals, birds, insects etc, are found in a region It influences the living style of people including settlement patterns, livelihood options, resource endowments, health ,and wellbeing It largely determines the agricultural activities, and the materials available for shelter and clothing Hence, people largely depend on ecosystem services for making of agricultural tools, building houses, hunting, etc. 2.4 CLIMATE CHANGE AND ITS CHALLENGES TO AFRICA’S DEVELOPMENT VISION At the end of this section, you will be able to: explain the major challenges of climate change on African development vision  Start up questions What is the difference between climate variability and climate change? What are the main causes of climate change in Africa? list out and explain the major causes of climate change in the continent. Discuss also on the indicators of climate change in Africa. How does climate change affect Africa’s development vision  Climate variability and Climate change In many cases climate variability and climate change are interchangeably used. However, there is a clear demarcation between the two. Their difference is time and what they encompass  Difference between CV and CC Climate change Climate Variability It is a long term or It is a short term permanent change in the state of the variations or climate system by fluctuations of average changes in the weather conditions average conditions such as El Nino or La and the variability of Nina, drought or flood, its properties, that hurricane, tornados persists for an It occurs due to natural extended period, typically decades or (internal) processes longer, whether due to within the climate natural and/or system or due to anthropogenic forces anthropogenic and drivers. (external)forces It is a long term It occurs with or alteration of average climatic conditions without our actions  Warm and cool large tropical areas of pacific El Nino and La Nina are opposite (warm and cool respectively) phases of ENSO ( Eli Nino Southern Oscillation), which is the most influential natural climate pattern on the earth, across tropical pacific ocean that swings back and forth every 3-5 years on average Eli Nino and La Nina affect both ocean and atmosphere. They disturb the atmospheric circulation and largest ocean basin-pacific ocean Eli Nino Shifts the average location and the strength of mid latitude jet streams, producing side effects on weather around the globe – easterly trade winds are weaker and warmer than usual, rainfall is below average (over Indonesia) or above the average (over the central and eastern pacific). It is the warmer tropical pacific waters that causes changes in global atmospheric circulation resulting in wide range of changes in global weather. La Nino Shifts the average location and the strength of mid latitude jet streams, producing side effects on weather around the globe – easterly trade winds are stronger and cooler than usual, rainfall is above average (over Indonesia) or below the average (over the central and eastern pacific). They are caused by weaker or stronger than the average easterly trade winds Why is CC happening and what are the causes? There are many natural and anthropogenic factors, that contribute to CC Today, CC is a great concern of worldwide Human population has increased –human activities increased - GHG in the atmosphere –INCREASED- absorb more heat radiation- global warming and CC WHAT ARE THE LONG TERM EFFECTS OF CC – Decrease in sea ice and the increase in sea level – Increase in permafrost thawing – Increase in heat waves – Decreased water resources in semi arid regions  Climate change in Africa It is an increasingly serious threat for Africans Africa is among the most vulnerable regions in the world to climate change. According to the Intergovernmental Panel on Climate Change (IPCC, 2001), the vulnerability of Africa to climate change is driven by a range of factors that include – weak adaptive capacity to its impact – high dependence on ecosystem goods for livelihoods, – less developed agricultural production systems. The risks of climate change on agricultural production, food security, water resources and ecosystem services will likely have increasingly severe consequences on lives and sustainable development prospects in Africa.  Most studies on climate change have … predicted that Africa is more likely to experience – higher temperatures ( 0.2 to 0.5oC by 2100)/decade – rising sea levels to coastal areas – changing rainfall patterns and – increased climate variability, all of which could affect much of its population. The actual and potential impacts of climate change in Africa are large and wide-ranging, affecting many aspects of people’s everyday lives. The Indicators or the signs of climate change of CC Higher temperatures, the drying up of soils, increased pest and disease, shifts in suitable areas for growing crops and livestock, desertification, floods, deforestation, and Soil erosion etc indicate that the signs of climate change is already happening. Therefore, climate change is one of the greatest environmental, social and economic threats facing Africa. The impact of climate change is more serious in poorest countries of the world, most of which are found in Africa. Poor people already live on the frontlines of pollution, disaster, and degradation of resources and land. For them, adaptation is a matter of sheer survival. Unfortunately, despite growing concern, no exact and reliable figures are available to quantify the economic costs of the negative impacts of climate change in Africa for either individuals or society as a whole.  As far as development is concerned, climate change will have a strong impact on Africa’s ability to achieve the Millennium Development Goals (MDGs) and the Africa 2063 goal and on its development policies in general, with increased pressure on agriculture, water supply and demand, health, and political stability. In general, African has been seriously affected by CC due to the following reasons. First, the African society is very closely coupled with the climate system, hundreds of millions of people depend on rainfall to grow their foods. Second, the African climate system is controlled by an extremely complex mix of large-scale weather systems. Third, the degree of expected climate change is large. The two most extensive land-based end of- century projected decreases in rainfall anywhere on the planet occur over Africa, particularly in North and South Africa. Finally, the capacity for adaptation to climate change is low.  To summarize Climate change in Africa is an increasingly serious threat for Africans as Africa is among the most vulnerable continents to climate change. Many climate models predict the negative impacts of climate change on agricultural production and food security in large parts of sub Saharan Africa (SSA). As far as development is concerned, climate change will have a strong impact on Africa’s ability to achieve the Millennium Development Goals (MDGs) and the Africa 2063 goal and on its development policies in general, with increased pressure on agriculture, water supply and demand, health, and political stability. One of the most important reasons for this is the continent’s low adaptive capacities to withstand the ever-changing climate conditions.  Evaluation What part of Africa is the most affected by CC? – From Central Africa Rep. to Somalia and Sudan are fragile states suffer from more floods, droughts, storm and other climate related shocks than other countries, when they have contributed the least to climate change – Of this south Sudan is the worst affected countries by Global warming. Home work REVIEW QUESTIONS Group 1 = 1 and 2 Group 2 = 3 and 4 Group 3 = 6 and 7 … … … … …